Current occupational health standards and prudence require that the fumes generated during welding be collected and disposed of, rather than allowed to fill the air of a welding shop or to be discharged to the outside air. Other industrial processes generate airborne particulate and create the same requirement.
Industrial filtering systems made and sold heretofore to fulfil the need range from costly large centralized systems to small units that are little more than shop vacuum cleaners. The present invention is concerned with portable units that are intermediate in cost between the foregoing extremes, but which work satisfactorily in industrial settings, insofar as requiring minimal maintenance, being durable, and having flexibility of use.
Fume collectors seeking to satisfy the foregoing commercial needs are known. Generally, they operate by capturing the fume bearing air in a vacuum hose attached to the welding device, drawing the air through a permeable filter media, such as a fabric bag, to extract the particulate, and discharging the cleaned air into the room or outside. Over time, the media become clogged and air flow diminishes. Thus, there is a need for periodic cleaning, since discarding clogged media can be overly expensive. In general, the manner of cleaning filter media depend on their configurations and the type of particulate. Among the more familiar methods applied to bag filters is a simple vigorous shaking. Another method is to impinge a pressure pulse on the filter walls. In more elaborate systems, the cleaning is automatic and periodic. Generally, the aims for cleaning are that the means have low cost, make low demand on the operator's time and attention, minimize the interruption of the essential filtering function, and maximize the life of the media. No one optimum is discernible from the literature or commerce.
A fume collecting system ought to be simple to use and maintain. The operator ought to be able to inspect the system easily, to clean and change the filter readily and conveniently, and to be assured that the system will reliably perform its intended air-cleaning function. Thus, the design of the system ought minimize the extent to which the operator gets dirty while doing maintenance.
Prior art devices have deficiencies in various of the foregoing aspects and thus there is a need for a device having an improved combination of features.